The world already ended once on The 100, and now it's about to end a second time. As we learned in the season three finale last year, the remaining nuclear power stations are melting down, and soon the earth will be overtaken by radiation...again.

"I thought it was a cool idea to tell an apocalypse within an apocalyptic story," executive producer Jason Rothenberg tells E! News about his decision to end the world that had already ended once. "One of the things I think we do on the show is put our characters in harder and harder situations. I think ultimately facing certain death is the final obstacle, and how they respond to that death sentence to me is interesting and revealing of character."

Let's just say that not everyone is going to handle their impending death via radiation very well at all.

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"We all know people who get terrible diagnoses, and some people fight tooth and nail, others break down," Rothenberg says. "I think we will see that happen across the board for our characters this season. I thought it was a fascinating dilemma to put in front of these people who have been through hell already, but you know, that's what this show is."

For most of the characters, the fact that the world is ending is only going to be made worse by the fact that Clarke (Eliza Taylor) just forced them out of the pleasant City of Light and back into harsh reality, where pretty much everything sucks.

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"In season four, what happens is we have to deal with the ramifications from Clarke taking everybody out of a situation where they were essentially safe," Rothenberg continues. "Their minds, their consciousness would live on in the City of Light, but to Clarke anyway, that's not real life. So now, people come back into their bodies and they realize that they're given back all their memories, their pain, and they find out on top of it that the world is going to end in six months and so they will not be, en masse, happy with Clarke probably going forward."

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If it sounds kind of unlikely that there's a chance to stop the nuclear meltdown, you're right. The question of this season, as it really is every season, is whether or not it's possible to survive.

"We're presenting a scenario which is not about how to do we stop it, it's about how do we survive it," Rothenberg says. "Can we survive it? Who gets to decide who survives? If there's not enough lifeboats on the Titanic, who gets them? Do we choose ourselves, do we choose our families, or do we choose our clans, or do we figure out a way to save everybody?"

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Clarke, of course will do her best to save everybody, because she learned from the best.

"She's sort of learned from Lexa that everybody is better and stronger together, and is now trying to figure out a way to do that, to save everybody, to look at everybody as one people. That's her journey this season."

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While the characters of the show are kind of primed for an apocalypse, the show's cast is a different story. Back at last year's San Diego Comic Con, we got Eliza Taylor, Lindsey Morgan, Marie Avgeropoulos, Richard Harmon, Henry Ian Cusick, and Christopher Larkin to judge their own roles in a hypothetical apocalypse. Be sure to watch the video above to find out who will lead, who will bring snacks, and who's pretty sure there's no chance they'd make it through alive.